Labour wants the Government to hire more social workers after a review report said workloads were too high.
Jacinda Ardern says nearly three-quarters are managing 19 or more children.
"The review is unequivocal - Child, Youth and Family needs more resourcing and it needs more social workers," said Labour's children's spokeswoman.
"Social workers are overloaded and unable to focus their time and energy on the kids they're tasked with protecting."
Social Development Minister Paula Bennett has accepted the review's conclusions and she's signalled there could be changes.
"We've still got far too many middle managers and not enough frontline social workers," she said.
"We've had an increase of about 140 (social workers) since 2006 but we've also had a massive increase in the number of middle managers and supervisors."
Ministry chief executive Brendan Boyle ordered the review and says it was "an honest and thorough analysis" of the day-to-day realities faced by frontline workers.
"Put simply, we've found that some of our social workers have too much on their plates," he said when he released the review report on Tuesday.
"This has gotten in the way of the most important part of their work - spending time with children and families."
Mr Boyle says work has started on alleviating the pressure of the social workers who have unmanageable workloads.
The report doesn't put a figure on the number of extra workers that are needed.
It says before that can be calculated there needs to be changes in the way they work so they don't have to spend so much time on reporting and administration.
Mr Boyle says a ministry-wide "modernisation project" will be launched.